1. Technical Background
The present invention relates generally to medical devices, and more particularly to a balloon catheter having an improved tip design.
2. Discussion
Balloon catheters are used in a variety of therapeutic applications, including many vascular treatments such as angioplasty. Angioplasty can be used to treat vascular disease, in which blood vessels may be partially or totally blocked or narrowed by a lesion or stenosis. In many instances of vascular disease, a local area of a blood vessel may become narrowed. This narrowing is called a lesion or stenosis, and may take to form of hard plaque, cholesterol, fats, or viscous thrombus. Such a stenosis may cause heart attack or stroke, which are significant health problems affecting millions of people each year.
During angioplasty, an expansive force may be applied to the lumen of the stenosis. This outward pressing of a constriction or narrowing at the desired site in a body passage is intended to partially or completely reopen or dilate that body passageway or lumen, increasing its inner diameter or cross-sectional area, to encourage greater blood flow through the newly expanded vessel.
As an example, the present invention will be described in relation to coronary, peripheral, and neurovascular angioplasty. However, it should be understood that the present invention relates to any angioplasty catheter having the features of the present invention, and is not limited to catheters for a particular therapeutic procedure.
Some balloon catheters have a relatively long and flexible tubular shaft defining one or more passages or lumens, extending between a hub at a proximal end to a distal end where the balloon is located. The catheter shaft may define an inflation lumen for conducting inflation fluid from an inflation port defined by the proximal hub to selectively inflate or a deflate the balloon, and may define a guidewire lumen extending from a distal guidewire port at the distal end of the catheter to a proximal port located at a position proximal from the balloon.
Among other things, the present invention relates to a balloon catheter having a tubular basic body with a distal end, a proximal end, and at least one inflation lumen extending between the proximal and the distal end, and a balloon close to the distal end which is connected with the inflation lumen, so that the balloon may be selectively expanded or by means of supplying an inflation medium under pressure through the inflation lumen.
Balloon catheters may be used for dilating a blood vessel in which a narrowing or stenosis has formed, or for delivering and deploying a stent, which is a tubular scaffold.
One consideration present in prior balloon catheters is to provide for maximum safety, even in the unlikely event of a balloon burst. The balloon is designed to withstand large inflation pressures, often as much as 12 atmospheres or more. Indeed, the rated burst pressure may often include an additional safety margin.
If a balloon does in fact burst or become punctured by a sharp edge on a stent or calcified lesion within a patient, it is desirable to further enhance the safety feature of the catheter. One possibility is that removal of some prior balloon catheters may be impeded when the balloon is torn. This challenge may be caused by remainders of the balloon attached to the balloon catheter, which may get caught on the guiding catheter introduction system, or may form a bulge such that the balloon may be difficult to pass through the guiding catheter. In rare occasions, the balloon may develop a xe2x80x9cradial tearxe2x80x9d around the balloon in a radial direction.
Tearing of the balloon may for instance be caused by sharp protrusions on a stent or a stenosis which has calcified and developed sufficiently sharp points to cause perforation of the balloon. It is also a remote possibility that the balloon of some prior balloon catheters may burst due to excessive pressure.
A possible object of the present invention is to provide a balloon catheter having additional safety features. To this end, a balloon catheter may be provided at least one longitudinal safety stop, which extends between the distal and the proximal ends of the balloon.
With a balloon catheter according the present invention, the desired additional safety features have been provided. The balloon preferably has a longitudinal structural feature for encouraging any balloon burst that may occur in rare instances to follow a generally longitudinal pattern, rather than a radial or transverse pattern.
In other words, the longitudinal safety stop of the present invention is intended to cause any possible tear in the balloon material to move toward the longitudinal safety stop and to follow it. One intended result of the present invention is that all of the balloon material remains connected to both the distal and the proximal ends of the balloon, and therefore also connected to the catheter shaft at both ends. Accordingly, it is more likely that all of the balloon material, even after any balloon burst, will remain attached to the catheter shaft up to removal from the patient through any guiding catheter or other delivery system that may have been used.
The present invention also provides a balloon catheter which minimizes any possibility that pieces of balloon material may detach from the balloon catheter.
In order to further enhance the safety features of the present invention, an alternative embodiment would be to include two or more longitudinal safety stops in the balloon material, which are preferably distributed evenly over the balloon.
Within the scope of the present invention different options are possible, such as a longitudinal safety stop extending in the longitudinal direction of the balloon catheter, or a safety stop extending in a helical pattern over the balloon in expanded state.
The present invention also encompasses an elongated element, such as a wire, which has been arranged in the material of the balloon. Such preferred embodiments can be effected in a relatively simple manner generally known in the art, which is advantageous for the production process.
These and various other object, advantages, and features of the invention will become apparent from the following description and claims, when considered in conjunction with the appended drawings.